couldnt you just cut a bunch of circles from flexible plastic. with a hole in the middle the size of the center tube and a radial slice.
then join them together with the on the radial slices so you have sort of a fat spring then just stretch it out to the right position and tack it to the rod, then reinforce it with fiber glass (or carbon fiber!)
heres an amazing graphic!
then join them together with the on the radial slices so you have sort of a fat spring then just stretch it out to the right position and tack it to the rod, then reinforce it with fiber glass (or carbon fiber!)
heres an amazing graphic!
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Neutron:
That's what I was trying to suggest awhile back in post 49 but you did it a lot better!
To seal the edges to the inside of the outer tube, maybe one could use a thick but still liquid glue and pour it into the cylinder and then rotate it to distribute it around the edges all the way down. It might take a few repetitions
That's what I was trying to suggest awhile back in post 49 but you did it a lot better!
To seal the edges to the inside of the outer tube, maybe one could use a thick but still liquid glue and pour it into the cylinder and then rotate it to distribute it around the edges all the way down. It might take a few repetitions
Not to drag this post up again, but I have stumbled upon that same web page and am considering building a pair of these strange devices.
It is late, and I am tired, but in my haze of sleep depravation, I am waxing philosophical.
That man who discovered pi... the constant upon which all musical mathematics are based , was Archimedes. If you recall, he also constructed a water-deploying device known as Archemedes' screw... which bears an uncanny resemblance to the spiral port in question.
If i recall, a helix is made of sinusoidal curves with the same periods and phases, one with an amplitude equlto the shell's inner radius, and the other equal to the center cylinder's outter radius. The sound waves produce their own force, as we know, which is in tangent to the inner curve as it enters the tube... suggesting to me that all those parameters can be optimised to suit our own evil designs.
NOW, I don't know what to do with that little brainstorm, but when I hear sinusoidal and amplitude... I think music. It would suggest that a properly designed and angled spiral port would indeed produce very little distortion.. but I'll leave that math until I have had some rest and coffee.
Consequently, many products use rigid helixs, so fabrication may not be neccessary. Conveyors and water pumps employ such devices. Maybe a pre-fabricated part with a suitable pitch can be purchased.
It is late, and I am tired, but in my haze of sleep depravation, I am waxing philosophical.
That man who discovered pi... the constant upon which all musical mathematics are based , was Archimedes. If you recall, he also constructed a water-deploying device known as Archemedes' screw... which bears an uncanny resemblance to the spiral port in question.
If i recall, a helix is made of sinusoidal curves with the same periods and phases, one with an amplitude equlto the shell's inner radius, and the other equal to the center cylinder's outter radius. The sound waves produce their own force, as we know, which is in tangent to the inner curve as it enters the tube... suggesting to me that all those parameters can be optimised to suit our own evil designs.
NOW, I don't know what to do with that little brainstorm, but when I hear sinusoidal and amplitude... I think music. It would suggest that a properly designed and angled spiral port would indeed produce very little distortion.. but I'll leave that math until I have had some rest and coffee.
Consequently, many products use rigid helixs, so fabrication may not be neccessary. Conveyors and water pumps employ such devices. Maybe a pre-fabricated part with a suitable pitch can be purchased.
I also came across the 3d spiral site and would love try it out. To me the disc method seems superior but very tedious. There is no problem sealing the spiral to the tube since they are one and the same. But I would hate to cut out all those small discs.
I'm not good at describing things but here is my suggestion. Create a form out of pvc tube that is the shape of the cutouts but thickness would be much larger. You would then pour something called papercrete or fibercrete (concrete and paper mixture) in the form. This material is far lighter then concrete and could be cut with regular wood saw. When the papercrete is firm you will unmold it and you will get a long shape that could easily be cut length wise like bread and you will get your individual slizes that would be the discs.
The form should be easy to construct with two different dimensions tubes and something resembling the "triangular" section of the disc...
When creating the spiral its easy to construct in different sections and coat the "staircase" with furhter papercrete so that its a smooth surface.
This to me sounds very easy especially if you want to construct several spirals by reusing your mold. This is the method that I will try...
Has anybody here tried the 3d spiral speakers yet?
As a final note, would this method be suitable to combine with multiple drivers? I am a novice when it comes to speaker design but I would love to use this method with some cheap NSB drivers that I have. I would use multiple drivers to keep their distortion down....Anybody know what size of enclosure would be good for the NSB?
Cheers.
Exipnos
I'm not good at describing things but here is my suggestion. Create a form out of pvc tube that is the shape of the cutouts but thickness would be much larger. You would then pour something called papercrete or fibercrete (concrete and paper mixture) in the form. This material is far lighter then concrete and could be cut with regular wood saw. When the papercrete is firm you will unmold it and you will get a long shape that could easily be cut length wise like bread and you will get your individual slizes that would be the discs.
The form should be easy to construct with two different dimensions tubes and something resembling the "triangular" section of the disc...
When creating the spiral its easy to construct in different sections and coat the "staircase" with furhter papercrete so that its a smooth surface.
This to me sounds very easy especially if you want to construct several spirals by reusing your mold. This is the method that I will try...
Has anybody here tried the 3d spiral speakers yet?
As a final note, would this method be suitable to combine with multiple drivers? I am a novice when it comes to speaker design but I would love to use this method with some cheap NSB drivers that I have. I would use multiple drivers to keep their distortion down....Anybody know what size of enclosure would be good for the NSB?
Cheers.
Exipnos
Here are my little mathematical musings on the spiral port.
Here are mu musings, hopefull it is beneficial. I am not the best with geometry, bt here goes:
FIRST THE MUSICAL PART:
Also, in music theory, pitch space is defined in helical terms... like the circle of 5th to represent octave equivalance and whatnot. Could be some interesting parallels there, I'm sure Pythagoras would agree. if a helix could be optimized to maintain proper pitch class across the octaves of the fundamental, then perhaps that would lend to an interesting purity of sound. it also suggests on the other hand, that an improper helix would cause an intonation imbalance, resulting in enharmonic dissonance.
NOW THE MATH:
This begs the question of who different applications of the helix will effect the mechanics.
The Cartesian logarithmic spiral, where there is a log increase in the geometric expression of the arms, or sometimes a hyperbolic spiral, is the one that I see used most in enclusires, usually made of rectangular channel extending perpendicular from the excursion axis of the cone... or parallel in the case of some TQWT's, and even in reverse sometimes... that is the basis of the horn enclosure. I suppose this could be re-created in 3D space by a conic helix.
But the spiral that we see in these enclosures is a simple arithmetic/Archimedian spiral with a cemi-circular corss section, stuffed into a cylindrical shell, where the each turn of the spiral maintains a constant distance between the arms... suggesting that is it were unfurled, it would be a loooooong, semi-circular port, so it's behavior is more like a folded, non-tapered transsmission line rather than a horn.
The math is parabolic, where the sides (directerix) at any given point are equidistant from the center (focus), as you can see in the equasions on his website. It seems like a modified and very compact Hemlholtz resonator, and it cleverly minimizes parallel planes, so you don't have to stuff it full of wool like a TL. That being said, i said MINIMIZES parallel planed, because the inner surface of the port and the outter surface of the center post form a parallel along the length of the tube. I feel that the double helix design may be slightly superior because of it's parabolic profile avoiding any parralel planed between the walls and the center post, and distortions caused by the presence of the center p[ost itself
CONCLUSION:
I'll be building up a pair this month for sure. It really is not that big a deal, so I'll just do it, and if it sucks, I'll just yank the spiral tube and use them as simple bass reflex enclosures in the 'ol workshop or something.
If anyne had a lathe or CNC, it would be a snap to make a dowel with a spiral groove, and then insert sticks or carbon rods and cover the whole thing in epoxy... or justmachine a spiral pattern out of a solid block of wood... like some old-time table legs that I have seen.
Also, an alternative to the single helix is a double helix, which might be able to be formed from a flexable material with some elasticity, and then cured with epoxy, or by intersecting the center axis of some rods with a central pin... or by simply makinf rigid cross-member lattices between two flexable axis (like solid core wire) and then twistng them into a dual sinusoidal helix pattern and coating them with epoxy.
Here are mu musings, hopefull it is beneficial. I am not the best with geometry, bt here goes:
FIRST THE MUSICAL PART:
Also, in music theory, pitch space is defined in helical terms... like the circle of 5th to represent octave equivalance and whatnot. Could be some interesting parallels there, I'm sure Pythagoras would agree. if a helix could be optimized to maintain proper pitch class across the octaves of the fundamental, then perhaps that would lend to an interesting purity of sound. it also suggests on the other hand, that an improper helix would cause an intonation imbalance, resulting in enharmonic dissonance.
NOW THE MATH:
This begs the question of who different applications of the helix will effect the mechanics.
The Cartesian logarithmic spiral, where there is a log increase in the geometric expression of the arms, or sometimes a hyperbolic spiral, is the one that I see used most in enclusires, usually made of rectangular channel extending perpendicular from the excursion axis of the cone... or parallel in the case of some TQWT's, and even in reverse sometimes... that is the basis of the horn enclosure. I suppose this could be re-created in 3D space by a conic helix.
But the spiral that we see in these enclosures is a simple arithmetic/Archimedian spiral with a cemi-circular corss section, stuffed into a cylindrical shell, where the each turn of the spiral maintains a constant distance between the arms... suggesting that is it were unfurled, it would be a loooooong, semi-circular port, so it's behavior is more like a folded, non-tapered transsmission line rather than a horn.
The math is parabolic, where the sides (directerix) at any given point are equidistant from the center (focus), as you can see in the equasions on his website. It seems like a modified and very compact Hemlholtz resonator, and it cleverly minimizes parallel planes, so you don't have to stuff it full of wool like a TL. That being said, i said MINIMIZES parallel planed, because the inner surface of the port and the outter surface of the center post form a parallel along the length of the tube. I feel that the double helix design may be slightly superior because of it's parabolic profile avoiding any parralel planed between the walls and the center post, and distortions caused by the presence of the center p[ost itself
CONCLUSION:
I'll be building up a pair this month for sure. It really is not that big a deal, so I'll just do it, and if it sucks, I'll just yank the spiral tube and use them as simple bass reflex enclosures in the 'ol workshop or something.
If anyne had a lathe or CNC, it would be a snap to make a dowel with a spiral groove, and then insert sticks or carbon rods and cover the whole thing in epoxy... or justmachine a spiral pattern out of a solid block of wood... like some old-time table legs that I have seen.
Also, an alternative to the single helix is a double helix, which might be able to be formed from a flexable material with some elasticity, and then cured with epoxy, or by intersecting the center axis of some rods with a central pin... or by simply makinf rigid cross-member lattices between two flexable axis (like solid core wire) and then twistng them into a dual sinusoidal helix pattern and coating them with epoxy.
I have found out, with a bit of research, that a wooden helix can be made pretty easily by most well equipped woodshops. "Barley twists" have been made for centuries using spokeshaves and chisles, but in modern day, a CNC lathe or a router lathe can do the job. Here are some examples:
http://legacywoodworking.com/
http://www.turningsunlimited.com/customturning.htm
That's probably the way I'll go.
http://legacywoodworking.com/
http://www.turningsunlimited.com/customturning.htm
That's probably the way I'll go.
Let me ammend my previous observations. Many of the spiral horns are indeed logarithmic spirals. I was looking at some of the earlier data and patent sheets, which used the Archimieds spiral. Which means of course that those designs are indeed expanding horns, and the math can be treated as such.
To me, without a CNC router, the easiest would be a popsicle stick type method, maybe using thicker rectangular balsa wood rods. This enclosure is definitely on my project list. I just wish we could get some more science into the equation regarding the behavior.
Before the horn project, I also want to play around with a straight helix as a subwoofer port. If the circular flow adds very little resistance, then large diameter acrylic or fake chrome helixes would be easily marketable. The "cool" factor would be higher than straight ports, plus they would be easier to fit in many boxes since their physical length is much shorter. Flared ends are inherent in the design, so just cut it to length using the formula you would have to include.
Before the horn project, I also want to play around with a straight helix as a subwoofer port. If the circular flow adds very little resistance, then large diameter acrylic or fake chrome helixes would be easily marketable. The "cool" factor would be higher than straight ports, plus they would be easier to fit in many boxes since their physical length is much shorter. Flared ends are inherent in the design, so just cut it to length using the formula you would have to include.
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